The short answer is: 1) How good is your track?; 2) How long and heavy is your train?
European operations have had fast push-pull trains since the early 1900s. But these were short, light passenger trains on well-manicured track, with fairly broad curves. Ulrich, you live in the area of GO Transit. Their push-pulls are up to around 10 cars long and move at full passenger speed on the Oakville Subdivision.
Trying that with a 5,000-ton freight train, even on good track with high-speed turnouts, would be dangerous because of the visibility issue plus long braking distance. The Oakville Sub is dead straight and practically level for most of its length, but I wouldn't want to push a long, heavy train over it at, say, 45 mph.
Assuming perfect track, I'd say "too fast" is the point ability to control the train exceeds visibility plus a safety factor of 50-100%.
Hi Ulrich,
You described watching trains switch cars in a yard. Most yard tracks are limited to 10 MPH, forward or reverse. And on the prototype most turnouts in a yard have a #8 frog and tracks are often made up of smaller jointed rails on older crossties. On mainlines operating on signal indication (not restricted speed) with a handful of cars and shoving through #20 turnouts in and out of sidings and through crossovers an engineer can be more aggressive. However if you're holding to a large cut of cars you'll probably keep it down because you definitely want to control the slack to keep from having a separation. That being said, from a safety standpoint an engineer always wants to be in control of his or her train allowing for a quick stop if necessary.
When shoving a cut of cars the engineer is relying on the ground person to direct the movement. This could be by hand signals with smaller cuts of cars but nowadays it is mostly done by radio instructions. Whenever I'm making shoving moves I'm constantly listening out for radio instructions by my conductor or looking out the window for hand signals. Also, if he or she is riding the shove move I'll want to make sure I don't apply the engine brake too hard to keep from slinging them off the end of the car (Like cracking a whip!). That may mean I need to apply trainline air or start slowly stretching the train out by braking sooner. A good engineer is like a skilled artist when it comes to efficient switching. Especially when some conductors idea of car lengths vary so much from the standard. They are trained in school that a car length is 50 feet. For some 50 feet is a 90 foot car and others it is a VW Beetle! LOL!
But to answer your question it really varies depending on the situation. If I'm on the mainline having just switched an industry and shoving a handful of cars back to a siding or a yard track moving on signal indication I might push it up to 40 MPH as long as the conductor has a good place to ride and wants to move. If I am shoving a yard track and the conductor says I'm clear for 25 to 50 car lengths I'll get it up to 10 MPH. If the conductor is only clearing me for 10 cars or less at a time I may only get up to 7 MPH. Once I'm down to 5 car lengths or less I start dropping my speed. At this point I'm now looking out the window straight down at the ground because this is the best way to judge my speed. Coupling up now at one car length away I may only be doing 2 to 3 MPH. While I'm doing this if I'm pushing cars up hill I'm using my throttle and if I'm on flat or downgrade I'm using the brakes to control the movement. If I'm spotting cars up at a precise spot I'm using a combination of power and brakes.
I hope this helps!
Tim
MidlandMike As has been noted, the mechanics of a passenger train are such that they can operate in the push mode, whereas freights are expected to push slowly. However, with distributed power, I have noted engines at the rear moving at track speed. If the rear engine was not totally pushing the last cars, then why would it be there. How is that mechanically different than a back-up move?
As has been noted, the mechanics of a passenger train are such that they can operate in the push mode, whereas freights are expected to push slowly. However, with distributed power, I have noted engines at the rear moving at track speed. If the rear engine was not totally pushing the last cars, then why would it be there. How is that mechanically different than a back-up move?
I think the key is that with Distributed Power, only the rear half* of the train is being shoved, and the rest is being pulled by the head end. That's still a considerable number of cars with today's trains, but it's not an entire train.
*there was an article in Trains Magazine on this a while ago, and I seem to recall the cars in the center were being both pulled and pushed equally, reducing the number of cars being only pushed. Can anybody clarify this, or am I imagining things?
There seems to be 2 issues: visibility and mechanics. As has been noted, the mechanics of a passenger train are such that they can operate in the push mode, whereas freights are expected to push slowly. However, with distributed power, I have noted engines at the rear moving at track speed. If the rear engine was not totally pushing the last cars, then why would it be there. How is that mechanically different than a back-up move?
The hospitals are crowded to overflowing with the injured and surgeons of Marshalltown and surrounding cities labored all night long in an effort to alleviate the sufferings of the unfortunates, may of whom have only slight chances for recovery.
The only plausible cause of the wreck yet conceived is that it was due to the fact that both engines drawing the passenger trains were backing, pushing their light tenders in front of them. The tender of the locomotive, it is said, is too light to hold the heavy piece of machinery on the track when a high rate of speed is being made.
http://www3.gendisasters.com/iowa/8060/gladbrook-ia-train-wreck-mar-1910-horrifying-disaster
How long have there been speed restrictions on backing moves?
Most railroads require yard movement to proceed at restricted speed, which is defined below..
From the GCOR
6.27 Movement at Restricted Speed
When required to move at restricted speed, movement must be made at a speed that allows stopping within half the range of vision short of:
or
When a train or engine is required to move at restricted speed, the crew must keep a lookout for broken rail and not exceed 20 MPH.
Comply with these requirements until the leading wheels reach a point where movement at restricted
speed is no longer required.
6.28 Movement on Other than Main Track
Except when moving on a main track or on a track where a block system is in effect, trains or engines
must move at a speed that allows them to stop within half the range of vision short of:
The actual speed limit is up to each railroad, but may not exceed the 20mph limit shown here, on my railroad yard speed is 10 mph max.
Each railroad may write their own rules more restrictive than these, but not less restrictive.
Current GCOR has combined rule 6.27 and 6.28 with both now listed simply as rule 6.28.
23 17 46 11
We can push at up to 20 MPH unless other restrictions apply. Of course, we're usually running only 3-5 cars.
The crew member "calling" the move must be qualified on the territory and maintain regular communications with the engineer. If there is someone waiting at a crossing, we are to stop and proceed.
We were stuck with an F on one of our operations last year, so every trip involved a push move in one direction. Even with a road switcher, there's no siding at the end of one of our trips, so a push move is always appropriate there.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Yes, I think several things have to be taken into consideration when answering this. First is the rules, timetable rules, operating rules, etc. of the given railroad. Second is a function of those rules: type of train, length of train, speed limit of track, diverging or straight route, weather and other visiblity factors. And third is the ability and skill of the engineer and his conductor or whoever is on the ground or on the hind end.
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On NS we are only allowed to shove as fast as restricted speed allows(15mph) At one time CSX's max shoving speed was around 25 or 30 mph, and even that was up to the discretion of the engineer. I'm not familiar with the rules on other RR's on their shoving speeds, but weight and the grade should be considered no matter where the move takes place. There are even restrictions on how many traction motors can be cut in on certain locos when shoving X amount of tons. Lots a variables.
What intrigues me about this question is that I was asked that exact question back in 8th grade almost 60 years ago. The answer is two fold. First...is of course the fact that a locomotive can operate at the same speed in either direction unlike an automobile. So, the speed forward or backward should be the same. But, back then especially, the answer was "slowly" because of the chance of jacknifing because of the designe and dynamics of a train. But today we have push-pull trains, passenger trains that usually can go the same speed in either direction and this is so because the train's cars and couplers have been designed to do it. (NJT's Operating Rules does note one set of cars has to operate fiver or ten miles slower in push than pull; not worth looking up at this point.) Freight trains of course are not so designed so their backward movement would have to be quite a bit slower than forward. Time has passed and the answer to the question has changed greatly.
I've heard that backing a train is a little bit like pushing a chain. I don't quite understand that, but my experience with hands on railroading is limited to 1/87 scale. The other day, on one of my usual Saturday afternoon forays to Bayview Junction with my son, we watched a train shunting back and forth out of the yard in nearby Aldershot. Alongside of us were a couple of railroaders from the US who watch trains on their days off. As we watched one CN back up I overheard one of the railroaders state " he's way too fast...no wonder CN puts so many on the ground". Judging speed is hard, especially when you're standing directly overhead on a pedestrian bridge, but the train did look like it was clipping along pretty good...and the engines seemed to be running wide open as they passed under us. So what is "too fast" when backing? Are there rules that govern speed while backing up or is that left to the discretion of the engineer?
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